In an air conditioning device for a vehicle, a refrigeration cycle device is operated by an engine for moving the vehicle. Accordingly, the refrigeration cycle device is stopped when the vehicle temporary stops moving and the engine is stopped. Recently, needs for an idle stop vehicle, in which the engine is stopped to improve fuel efficiency when the vehicle stops moving for waiting for a traffic signal, is increased. The idle stop vehicle may not give sufficient comfortable feeling to a passenger in a vehicle compartment since the refrigeration cycle is stopped when the vehicle stops moving (i.e., when the engine is stopped). In addition, the fuel efficiency may deteriorate when the engine is re-started to secure the comfortable feeling while the vehicle is stopped.
Patent Literature 1 discloses a technique to solve the above-described issues. Specifically, Patent Literature 1 discloses an interior heat exchanger having a cold storage function to maintain the comfortable feeling while the engine is stopped. More specifically, Patent Literature 1 discloses that a cold storage reservoir, in which a cold storage material is disposed, is located downstream of a conventional evaporator. The cold storage material stores cold heat while the vehicle moves and uses the cold heat while the vehicle is stopped.
Patent Literature 2 discloses that a cold storage reservoir having a small capacity is located adjacent to tubes configuring refrigerant paths of the evaporator, and a cold storage material is disposed in the cold storage reservoir. In addition, Patent Literature 3 discloses that a normal paraffin that has high solidification and melting characteristics, which is kept stable for a long time, and has high-temperature latent heat.
Patent Literature 4 discloses that a threshold temperature is set to be higher than a temperature of air blown by an air conditioner when the vehicle moves and to be capable of securing the comfortable feeling, such that a stopping time of the vehicle is extended in an idle stop. According to Patent Literature 4, the temperature of air blown by the air conditioner becomes higher than or equal to the threshold temperature, an air conditioning request is made and an engine is re-started.